The invention relates to a radiation-polymerizable mixture comprising a polymer binder, a compound polymerizable by free radicals and a compound capable of initiating the polymerization of the polymerizable compound under the influence of actinic radiation and to a recording material containing this radiation-sensitive mixture.
Photopolymerizable mixtures for the production of printing plates, photoresists and other light-sensitive materials contain compounds which can be polymerized by free radicals and polymerize upon exposure to light in the presence of a photoinitiator to give crosslinked insoluble products. Compounds of this type have previously been almost exclusively esters of unsaturated carboxylic acids, in particular of acrylic and methacrylic acid, with polyhydric aliphatic or cycloaliphatic alcohols which, if desired, may contain urethane or ether groups. In prior publications, for example in U.S. Pat. No. 2,892,716, divinyl esters of aromatic or aliphatic disulfonic acids are also mentioned as polymerizable compounds. However, these compounds have not been introduced into practice.
The previously preferred (meth)acrylates of polyhydric alcohols have, at least for some applications, specific disadvantages. They are unstable at elevated temperatures, for example above 150.degree. C. Many of the low-molecular-weight representatives are highly volatile, and this volatility becomes noticeable in the layer upon prolonged storage and during processing at elevated temperatures. Moreover, the majority of the preferred representatives are water-insoluble and thus more difficult to combine with water-soluble or hydrophilic binders. In addition, most (meth)acrylates caused troublesome irritations of the skin.
Esters and other derivatives of alkenylphosphonic and alkenylphosphinic acids with mainly monohydric alcohols are known and are used on a large scale for the preparation of polymers, for example of polyvinylphosphonic acid and its derivatives. The unsaturated compounds mentioned have hitherto been utilized directly--except for the preparation of polymers--only to a small extent, in which virtually only the acidic properties of the monomers were utilized without making use of the polymerizability of the alkenyl group. This can be probably explained by the relatively low polymerization tendency of the known alkenylphosphonic acids or their derivatives (DE-B 1,106,963/1,135,176 =U.S. Pat. No. 3,297,663).
Nevertheless, the prior German Patent Application P 3,817,424.8 has described radiation-curable mixtures containing alkenylphosphonic and -phosphinic esters of 1,1,1-tris(hydroxymethyl)alkanes and 2,2-bis(hydroxymethyl)-1,3-propanediol as monomers.